DESCRIPTION: (adapted from the application): To determine the impact of an experimental intervention on aging, it is essential that an investigator have knowledge of how the intervention alters the pathological lesions that occur with age. Pathological information also provides investigators with insight into the potential biological/molecular mechanism(s) of the intervention. The pathology core (Core C) will provide investigators in the three projects with detailed pathological analyses of the lesions that occur with age in colonies of aging transgenic and non-transgenic mice fed ad libiturn and 60% ad libitum (dietary restriction, DR). The three transgenic mouse models studied are: DNA polymerase p heterozygous (p-po1 -/+) knockout mice, transgenic mice over expressing the GLUT-4 glucose transporter protein, and null CRH (corticosterone releasing hormone( knockout mice. The pathology associated with aging also will be determined in mice given corticosterone supplementation in project 3. In addition, the pathology Core will provide the developmental core (Core D) with assistance in determining in tetracycline administration to transgenic mice results in any detectable pathology. The specific aims of the pathology core are: (1) To conduct comprehensive pathological analyses of the transgenic mice and their litter mates that die spontaneously in the aging colonies maintained in the animal core (Core B). (2) To conduct end of life and cross-sectional pathological analyses on mice given corticosterone supplementation. (4) To assist investigators with pathological analyses of specific tissues that are studied by a project or core.